1. Field of the Invention
The present invention relates to a device for removing excess liquid from an image receptor and, more particularly, to a device for removing excess liquid after an image on an image receptor has been developed using liquid development techniques.
2. Description of the Related Art
In one liquid development technique, an image receptor having a photoconductive surface is moved past: 1) a charging station at which the receptor surface is provided with an electrostatic charge; 2) an exposure station at which the receptor surface is exposed to a light image of an original selectively to discharge the surface and form an electrostatic image; 3) a developing station at which a liquid developer is applied to the surface to form a toner particle image on the surface; and 4) a transfer station at which the developed image is transferred to a sheet of paper. The toner, or colorant, applied at the developing station is held to the image areas by electrostatic or other surface forces. A liquid layer remains both on the image and on the background areas. The excess liquid often results in damp or stained paper copies. Excess liquid also creates a problem in other liquid development techniques such as, for example, the ionographic and ion deposition techniques.
Various techniques have been developed to remove excess developer material without disturbing the delicate developed image on the photoconductive surface.
U.S. Pat. No. 4,181,094 to Gardiner discloses an apparatus for removing excess liquid developer from the surface of a photoconductor carrying a layer of developer liquid of a predetermined thickness. A mechanical barrier member formed with a slot extends across the photoconductive surface and is in close relationship to the surface with a gap between the barrier member and the surface which is less than the thickness of the developer layer. Low pressure air is supplied through the slot to form an air pressure barrier in the region between the barrier member and the photoconductive surface which prevents the passage of a relatively thick layer of developer liquid. A sponge pad is used to wipe the barrier member for the removal of developer liquid and for the prevention of toner deposit buildup which may be present.
U.S. Pat. No. 4,014,065 to Hudson discloses a vacuum removal device for removing excess developer material from a member having a latent image developed with magnetic developer material. The vacuum comprises a chamber having inlet and outlet ports sufficiently small to ensure substantially uniform air flow. The inlet port is in communication with a means for effecting a uniform shearing air flow across the developer material on the latent image member, thereby removing developer material from background portions of the latent image member. The cross-sectional area of the inlet port can be varied to meet varying air flow requirements.
U.S. Pat. No. 4,067,018 to Pond discloses a displacement system which removes excessive magnetic developer material from the vicinity of a latent image by application of air streams along the developed surface of the image. The system uses a vacuum assembly. A centrifugal force is applied to the image surface to displace excess particles. Particle-laden air flow moves in a path substantially parallel to and opposite to the path of travel of the image surface.
U.S. Pat. No. 4,721,661 to Olson et al discloses a vacuum device for selectively removing excess toner from an image member. The device minimizes tangential air flow across the surface of the image member by using a suction device terminating in lips whose terminal face along an edge are parallel to one another.
U.S. Pat. No. 4,797,708 to Kasiske, Jr. et al discloses an apparatus for scavenging unwanted particles from a photoconductor of an electrographic device. The particles are removed by a vacuum system including a plenum having an inlet opening closely adjacent the surface of the photoconductor. The plenum is mounted for movement toward and away from the photoconductor so that it closely follows photoconductor movement and precisely maintains its position with respect thereto.
U.S. Pat. No. 3,536,528 to De Geest discloses an electrostatic cleaner which removes fine particles from flexible sheet material. The cleaner is primarily used with photographic film for removing fine particles by electrically charging the surface of the sheet and removing the particles by air currents produced by a suction or blowing device. The air currents impinge obliquely onto one surface of the sheet material. A stream of pressurized air is provided to an opposite sheet surface. This stream becomes laden with particles and is carried off through a channel.
U.S. Pat. No. 4,121,947 to Hemphill discloses a method of cleaning a photoreceptor by exposing a photoconductive layer of the photoreceptor to light, charging the layer, vibrating the photoreceptor to dislodge toner and subjecting the dislodged toner to a force, either vacuum or gravity, to draw the toner away from the photoreceptor
U.S. Pat. No. 4,260,235 to Stack discloses a contamination prevention system which includes a vacuum scavenging chamber which establishes a venturi to remove toner particles entrained in a boundary layer.
While the related art recognizes that air pressure can be effective in removing excess developer material, the art does not recognize the advantages of driving the air flow with sufficient speed through a channel adjacent to the receptor surface to create a pressure gradient for enhancement of the removal of excess developer material.